Guan Hui Inter-city Dalang Station Deep Foundation Pit Excavation On Surrounding Buildings

With the development of urban construction, the subway station foundation pitengineering is often in both buildings nearby, study the effect of excavation on thesurrounding buildings is of great significance. this paper Combining with inter-cityDaLang station of large foundation pit excavation effect on neighboring buildings inthe process of practical engineering problems, based on field measurement and3dnumerical analysis method to study the effects of deformation of foundation pitexcavation on nearby buildings and main research results are as follows:(1) To study the influences caused by foundation pit excavation construction aroundthe deformation mechanism, deformation of the surrounding buildings is mainlycomposed of the pit uplift, deformation of retaining structure and soil settlement ofsurface caused by these three factors.(2) Through the engineering experimental research, this paper analyzes theoundation pit excavation process occurs, even around the wall horizontaldisplacement, the surface settlement, the surrounding buildings settlement, concretesupport and steel support axial forces change rule. The whole excavation process,and even the wall horizontal displacement increases with the increase of excavationdepth, the final horizontal displacement curve presents the "belly" form; Firstmeasured axial force of concrete supporting in foundation pit excavation at large, asthe name of the second steel support the erection of reinforced concrete strut axialforces gradually decreases, and the name of the second steel support axial forces inthe third steel support after the completion of the erection, the axial force is alsogradually decreases, and finally stability; Surrounding ground settlement and thesettlement of buildings with similar laws, roughly experienced three stages, smalldeformation stage, accelerating development stage, slowly changing final steadystage, the ground settlement around the maximum does not appear at the edge of thefoundation pit, but where11m distance of foundation pit excavation depth (0.5times), in the foundation pit of20m (1times the depth of excavation surfacesubsidence is smaller. (3) The numerical simulation, the buildings and the excavation of the distance, as thebuilding foundation pit is more and more far, the structure of the absolute settlementgradually decreased, but differential settlement of buildings with the increase ofdistance, bigger and smaller. Building its own load, load of building is absolutesettlement and differential settlement affect building a very important factor, withthe increase of building load, the structure of the absolute settlement increase rapidly,differential settlement, slow development and first when increased to a certaindegree, differential settlement is also increasing rapidly. Too much building loadwill cause plastic deformation.(4) The buildings surrounding the absolute settlement and differential settlement offoundation pit with even the wall decreases with the increase of stiffness, but eventhe local stiffness of the wall increase to a certain extent, reduced settlement value isnot very obvious. Increase the capacity of the wall will reduce the absolutesettlement of surrounding buildings and difference, but even to even the grave of thewall of the wall depth reaches a certain size, continue to increase the depth of thesoil, the effect is not very obvious. Steel support pre axial force, axial force whenthe additive75%design of axial force, continue to increase the axial force effect isnot obvious. Order of foundation pit excavation and erection of support is a veryimportant factor to influence building subsidence, first set up support afterexcavation construction ways than after the first excavation support mode ofsettlement is much smaller.(5) The main factors influencing the settlement of buildings for the building fromdistance, building its own load, supporting and excavation construction sequence,followed by the capacity of the wall and additive of steel support axial forces, andeven the stiffness of the wall are relatively less affected.